566. The radius of a circle is increased by 1%. How much does the area of the circle increase ?
     

1. 1. 1%
      

   
   
   

   2. 1.1%
      

   
   
   

   3. 2 %
      

   
   
   

   4. 2.01%

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 10,
   

   %Effect on area =		1 + 1 +	1 × 1		% = 2.01%
   			100

   Correct Option: D

   Using Rule 10,
   

   %Effect on area =		1 + 1 +	1 × 1		% = 2.01%
   			100

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567. In measuring the sides of a rectangle, there is an excess of 5% on one side and 2% deficit on the other. Then the error percent in the area is
     

1. 1. 3·3%
      

   
   
   

   2. 3·0%
      

   
   
   

   3. 2·9%
      

   
   
   

   4. 2·7%

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 10,
   

   Required net effect =		x + y +	xy		%
   			100

   
   

   Negative sign shows decrease =		5 - 2 -	5 × 2		% = 2.9%
   			100

   Correct Option: C

   Using Rule 10,
   

   Required net effect =		x + y +	xy		%
   			100

   
   

   Negative sign shows decrease =		5 - 2 -	5 × 2		% = 2.9%
   			100

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568. The length and breadth of a square are increased by 30% and 20% respectively. The area of the rectangle so formed exceeds the area of the square by
     

1. 1. 46%
      

   
   
   

   2. 66%
      

   
   
   

   3. 42%
      

   
   
   

   4. 56%

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 10,
   

   Percentage increase in area =		30 + 20 +	30 × 20		% = 56%
   			100

   Correct Option: D

   Using Rule 10,
   

   Percentage increase in area =		30 + 20 +	30 × 20		% = 56%
   			100

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569. If each edge of a cube is increased by 40%, the percentage increase in its surface area is
     

1. 1. 40%
      

   
   
   

   2. 60%
      

   
   
   

   3. 80%
      

   
   
   

   4. 96%

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 10,
   

   Required percentage increase =		40 + 40 +	40 × 40		% = 96%
   			100

   
   Or
   Let edge = 10, S. Area = 600,
   New edge = 14 ⇒ New surface area = 6 × 142 = 6 × 196 = 1176.
   

   % increase =		1176 - 600		100
   		600

   
   

   =	576	= 96%
   	6

   Correct Option: D

   Using Rule 10,
   

   Required percentage increase =		40 + 40 +	40 × 40		% = 96%
   			100

   
   Or
   Let edge = 10, S. Area = 600,
   New edge = 14 ⇒ New surface area = 6 × 142 = 6 × 196 = 1176.
   

   % increase =		1176 - 600		100
   		600

   
   

   =	576	= 96%
   	6

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570. If the diameter of a circle is increased by 8%, then its area is increased by :
     

1. 1. 16.64%
      

   
   
   

   2. 6.64%
      

   
   
   

   3. 16%
      

   
   
   

   4. 16.46%

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using Rule 10,
   

   Required percentage increase =		8 + 8 +	8 × 8		% = 16.64%
   			100

   Correct Option: A

   Using Rule 10,
   

   Required percentage increase =		8 + 8 +	8 × 8		% = 16.64%
   			100

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